During the manufacture of semiconductor devices, photoresist is used to form a pattern which is then transferred to a film, such as a magnetoresistive metal film, using an etch process. The resolution of the features of the photoresist pattern is limited by the optical exposure system. Near the limit of resolution of the optical exposure system, sharp corners and pointed structures may become rounded.
Others have used a high contrast photoresist to increase the resolution of the photoresist. The contrast of a photoresist is measured by the factor gamma. The value of gamma is defined as [log10E0/Ei]31 l, where E0 is the energy where the exposed resist is completely removed and Ei is the threshold energy where the exposed resist first exhibits significant removal. Typical values for gamma range from 1 to 10.
Others have employed a serif that can be used to reduce rounding of sharp corners in the photoresist.
Use of high contrast photoresist and serifs can eliminate much corner rounding that occurs in lithography. However, in the case of manufacturing a pointed end to a device, there is still significant rounding.
Manufacturing devices with very pointed ends is difficult to accomplish near the resolution limits of the optical exposure system. The uses of high contrast photoresist and serifs have been found to not transfer a pointed shape well to the underlying film.
Therefore, there is a need for novel methods to create sharp pointed structures.
Therefore, there is a further need for such novel methods to create sharp pointed structures in a semiconductor based structure.
Therefore, there is a further need for such novel methods to create sharp pointed structures in magnetoresistive metal film.